Temperature-dependent polarization evolution of photoluminescence in Ruddlesden–Popper perovskite (PEA)2SnI4

Abstract

Ruddlesden–Popper (RP) tin halide perovskites attract lots of research interests for opto-electronic devices because of its smaller optical bandgaps, smaller effective masses for carriers and are less toxic compared to its lead-based counterparts. Lots of optical characterization have been done but discussion of polarization is relatively few. We use linear and circular polarization resolved spectroscopy to investigate the polarization property of (PEA)${}_2$SnI${}_4$ from 4 K to room temperature and under external magnetic field, since polarization is a new degree of freedom for opto-electronic devices. We found that the absorption and photoluminescence of excitons in (PEA)${}_2$SnI${}_4$ is linear polarized, and the degree of linear polarization decreases from 0.6 at 4 K to 0.08 at 290 K, and degree of circular polarization is zero. The polarization direction can be rotated by magnetic field at 2.4 deg per tesla. We also observed exciton fine structure of the band edge bright exciton, the energy splitting of two orthogonal states is only 3 meV. Our findings on such polarized exciton property can be benefit for opto-electronic devices application.